More than 2,500 people were killed in Juarez last year, according to media reports, making it one of Mexico's most violent cities. Attacks have surged in response to President Felipe Calderon's war on drugs.

Public Security Minister Genaro Garcia Luna said in an interview with Televisa network on Wednesday the reinforcements would arrive over next few days. "It adds new capacities to the (fight) against crime," he said.

A spokesperson for the interior ministry said the plan was to replace the 10,000 troops now patrolling the industrial city across the U.S.-border from El Paso, Texas.
Calderon deployed thousands of soldiers after taking office in late 2006. His strategy scored major recent victories with the capture of a key Tijuana drug gang leader on Tuesday and the killing of the head of Beltran Leyva cartel in western Mexico.

But the army clampdown has ignited brutal turf wars between rival gangs, killing 17,000 people over three years.

The army has replaced many policemen suspected of working for drug groups, but human rights watchdogs have documented serious abuses by soldiers and say the military should not be charged with civilian duties.

One activist who blamed the army for her son's abduction and demanded that troops leave the city, was killed in Juarez this month, sparking protests.

The army has acknowledged it has been unable to stop the warring cartels fighting for control of smuggling routes into the United States.